WATERPROOF - Made of high quality oxford waterproof fabric, durable and wearproof, avoiding the appearance of wet work, protect your papers inside dry when you walking outside in rainy daySHOULDER STRAP - With 2 sketch paper storage pockets at each side internal(when drawing board is closed by buckle), as the drawing board external, one side with shoulder straps, it is for back carrying, the other side can be used as sketch board, use a clip, take your paper and pencil, you can start to draw or sketchSIZE - 17.7 x 13.7 inch(45 x35 cm),suitable for A3, A4 sketch paperLARGE CAPACITY - The sketch board can store about 40 sheets 8K drawing papers and the double velcro closures are securerDOUBLE SHOULDER - It has 2 shoulder straps, adjustable with buckle, you can adjust it for convenient shoulder/back carry, very good for artist go out to sketch from nature, copy, paint or draw